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Electrostatic self assembly of Carbon Nano-tubes

R.H. DetigElectrox, US

Keywords:CNT transistors, sensors, self assembly virgin materials

Abstract:Using techniques developed from the electrostatics industry “ropes”of virgin carbon nanotubes are pulverized into individual tubes which are immediately self assembled between two electrodes on a dielectric surface. A voltage of a few hundred volts exists between these electrodes. Such structures can be used as chemical sensors or field effect transistors. We will describe both the self assembly process and the pulverizing process. One advantage our technique is that no surfactants or wetting agents of any kind are used. The nanotubes have no net electrochemical charge (i.e. no surface functionality and no charge director materials are used). The virgin nanotubes are electrically conducting so they align along electrical field lines. II Discussion: Building Sensors or Field Effect Transistors (FET’s) Using Virgin CNT’s By virgin nanotubes we mean SWNT’s with no surface functionality per se; no wetting agents and surfactants are employed, nor are there any poly-electrolytes (charge directors) added to the diluent. The sensor/transistor assemblies are created between two electrodes on a dielectric surface with gaps between electrodes (called the channel) that ranging from a few microns to as much as 50 microns. Much smaller gaps are also easily produced. The channel widths extend from a few to 10’s of microns range. We will discuss the theory behind the operation of this fiber self assembly process and show samples of typical parts, which display transistor behavior. In typical sensor applications, functional surface coatings are added after the fact of assembly; and there may be as many as two dozen of them for a single family of sensors. Beyond the obvious application of building sensors, the process can also assemble the channel of a high performance, field effect transistor; as CNT’s have 100 times the mobility of single crystal silicon, the cornerstone of all electronics. Such parts are useful for phased array radars and backplanes for flat panel displays. Author Biography Robert H. Detig founded Electrox Corporation in 1992 to apply electrographic imaging technology as a manufacturing tool for various industries. He holds some of the fundamental patents on the photo-polymer electrostatic printing plates and functional liquid toners. He was awarded a PhD in Electrical Engineering by Carnegie-Mellon University in Pittsburgh, Penna.